Salmon, other marine species will move north as water warms

Orcas, gray whales, sharks and salmon: Climate change will push West Coast marine species northward at an average of 30 kilometers (nearly 20 miles) a decade, according to a new study by U.S. and Canadian scientists. Orcas in Washington coastal waters, which feed on salmon, are already endangered. VALERY HACHE/AFP/Getty Images)

Changes in climate, in large part caused by humans, will drive West Coast marine species, from whales to salmon, northward by an average of 30 kilometers (nearly 20 miles) a decade, according to a new study published in the journal Progress in Oceanography.

The shift will be especially notable in Alaskan waters. For instance, the gray whales, which migrate from Baja California to Alaska each year, are moving north out of the the Bering Sea into Arctic waters of the Chukchi Sea.

“Marine life is being affected by changes in ocean conditions resulting from changes in climate and chemistry triggered by combustion of fossil fuels,” said the study, the work of scientists from the National Oceanic and Atmospheric Administration, and the Universities of British Columbia and Victoria.

The study suggests that species, shifting with warming oceans, will move into habitats occupied by other marine life, particularly in northern areas of the Gulf of Alaska and Bering Sea.

At the same time, some will disappear from areas at the southern end of their ranges, especially off Oregon and California.

“As the climate warms, the species will follow the conditions they’re adapted to,” said Richard Brodeur, a NOAAA fisheries scientist and the study’s coauthor.

“We’re going to see more interactions between species and there will be winners and losers that we cannot foresee,” Brodeur added.

The salmon fishery off Barkley Sound on Vancouver Island has already been impacted: Chub mackerel, moving north, have devoured young salmon as they head out into the Pacific Ocean from from the Robertson Creek Hatchery.

“Warmer water species are expected to become increasingly dominant in the region,” the scientists predicted in their study.

The researchers in the study estimated changes in the distribution of 28 near-surface fish species usually collected in research surveys done in northeast stretches of the Pacific Ocean. They used established climate global models to project how fish distribution will shift by 2050, with greenhouse gases warming the atmosphere and ocean surface.

“Nothing is certain,” said Brodeur, “but we think we have a picture of the most likely changes.”

Other species shifts are already underway. Predatory Humboldt squid from Central and South America have invaded the West Coast of North America. Albacore have shifted to more northerly waters. Eulachon (candlefish) have disappeared from warning waters at the southern end of their range.

“Thinking more broadly, this reshuffling of marine species across the whole biological community may lead to declines in the beneficial functions of marine and coastal ecosystems,” said Tom Okey, a Pew fellow in marine conservation at the University of Victoria, and another coauthor.

The lead author of the study is University of British Columbia fisheries professor William Cheung.

The study anticipates warm-water species will move north with ocean warming. Mackerel are already on the move. Thresher sharks are identified as another species.

What will be the impact? Some predators, notably sea lions and sea birds, which raise their young in fixed rookeries or colonies, may find fish harder to find and moving beyond their usual foraging ranges.

“If their prey moves farther north, they either have to travel farther and expend more energy to get them, or find something else to eat,” said Brodeur.

“It’s the same thing for fishermen. If it gets warmer, the fish they depend on are going to move up north and that means more travel time and more fuel will be needed to follow them, or else they may need to switch to different target species. It may not happen right away, but we are likely to see that kind of a trend.”

The scientists’ findings were released just as leaders in Congress, rushing to complete an FY 2015 spending bill, put in $65 million for the Pacific Coastal Salmon Recovery Fund. The figure represents a $15 million increase over what President Obama recommended.

The recovery effort is being mounted as rivers warm, with hungry predators such as chub mackerel moving north.